What parameters are defined in a transformer oil specification?

Specifications define required dielectric and chemical performance limits and the test methods used. Typical parameters include breakdown voltage, moisture content, acidity, dielectric dissipation factor, resistivity, interfacial tension, viscosity, density, flash and fire points, pour point, oxidation stability, and sometimes inhibitor type and concentration. Some specs include corrosive sulfur requirements, gassing tendency, PCB limits, and compatibility expectations for materials. Procurement specs also define packaging, cleanliness requirements, sampling and acceptance procedures, and documentation such as certificates of analysis and SDS.